Identification of co-expressed networks and key genes associated with organic acid in peach fruit

Malate, citrate, and quinate are the major organic acids in ripen peach fruit, the content of which undergoes considerable variations during fruit development and maturation. The molecular mechanisms underlying these variations remain largely unclear. In this study, weighted gene co-expression network analysis (WGCNA) of two accessions in five developmental stages was performed to identify networks and key genes associated with main organic acids. The obtained hubgenes were screened by comparative transcriptome analysis of 102 peach accessions. Combined with functional annotation, three genes encoding WRKY50, MYB62, and cation/H+ exchanger 18, respectively, were detected as candidate genes related with malate content. One gene encoding bHLH1 was considered as candidate genes associated with citrate content. The four candidate genes were validated by integrated analysis of phenotype and expression analysis of ‘Jintong 5’, a randomly selected accession. These findings provide new sight to our existing knowledge of organic acid regulation in peach.